Added foundation for sway-fmt v2

[eureka-cpu]

The design of rustfmt is to leave code functionality in tact, but also do more than just move white space. For instance, long generic parameters can be cleaned up with a where clause addition and formatting of those parameters after it. I think that's a really great characteristic that keeps code uniform and even teaches users the standard practices.

It uses an AST for most of the formatting, but for macros it uses tokens or otherwise leaves them untouched. Most macros aren't formatted, unless necessary like the format! macro since it takes in variables that result in a String.

rustfmt can recognize when something won't benefit from being formatted and opts that portion of the code out of the formatting process. If code doesn't fit the conditions of what would need formatting, e.g. a user created diagram, then it will just leave it alone.

swayfmt's goal is to be somewhat transparent. It should format Sway code to our standards, and if the user so decides it, they can add a swayfmt.toml to their root dir and it will assume only the changes present, and leave the rest to default.

Tracking further development: #1516

[mitchmindtree]

Getting close!

[mitchmindtree]

Only things left are:

• Change version to 0.0.0.
• Add publish = false flag in favour of eventually publishing as sway-fmt when it's ready.

After these I'm happy to approve!

[mitchmindtree]

🥳